Manganese dioxide (MnO.sub.2) has been used as a main material for batteries for many years. The basic components of a lithium manganese oxide cell typically include a lithium anode, a separator or solid electrolyte, and a manganese oxide cathode, typically of MnO.sub.2. The cathode usually contains other components such as graphite and an electrolyte binder, to facilitate ionic and charge transport during operation of the cell. Compounds of manganese in the +2, +3, +4, +5, +6 and +7 oxidation states are known, but many are unstable in the solid state. The ion Mn.sup.+4 (MnIV), is known to be stable in the solid state, although the chemistry of manganese (IV) is not extensive. Virtually, the only stable compound of manganese in this state is the MnO.sub.2 which is used as a cathode material. In the reaction of the Li/MnO.sub.2 battery, Li+ ion is introduced into the MnO.sub.2 crystal lattice. Although the MnO.sub.2 oxide may have acceptable capacities for lithium insertion into the lattice, the insertion reaction takes place over a relatively wide voltage range. Therefore, it is not possible to utilize the full capacity of the cathode materials in practical applications. Furthermore, manganese oxides are unstable under conditions of discharge, and when cycling during use is extended from a few cycles to tens of cycles. What is needed is a new cathode active material based on oxides of manganese in a form which maintains capacity and good charge/discharge characteristics over its useful life.